RSD Puzzle #021

H. Hooshmand, M. D.

DIPLOMATE AMERICAN BOARD OF PSYCHIATRY AND NEUROLOGY

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EPILEPSY, PAIN, MS

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RSD PUZZLE #21
Symptoms used to diagnose RSD

"I have suffered from RSD for the past eight years. In the first few years, sympathetic nerve blocks helped me. Last month the doctor did a diagnostic sympathetic nerve block which did not relieve my pain. The doctor says that I do not have RSD because the diagnostic test ruled it out. How can I not have RSD when I have had all the other findings of it in the past eight years?"

One of the most accurate ways of diagnosing RSD in a patient who has had other manifestations of it (constant burning pain, weakness or movement disorder of the extremity, emotional disturbance, and insomnia, as well as evidence of swelling and inflammation of the extremity) is to do a sympathetic ganglion or IV Phentolamine) tests. In the first two to three years, such a sympathetic nerve block test definitively relieves the patient from her pain. Such a positive response of pain relief proves that the patient suffers from "SYMPATHETICALLY MEDIATED PAIN" (SMP).

However, after two to three years of suffering from RSD, the longstanding poor circulation and constriction of the blood vessels as well as the inflammation and swelling secondary to RSD, affect the non-sympathetic (somatic) nerves as well. So the patient develops not only SMP but also the pain that is independent of sympathetic system function due to the lack of oxygen to the somatic nerve fibers (non-sympathetic nerve fibers). This type of pain, which does not respond to sympathetic nerve blocks, is called "SYMPATHETICALLY INDEPENDENT PAIN" (SIP).

The end result is that longstanding RSD causes the development of a pain that is independent of the sympathetic system due to the poor circulation and the swelling. The patient develops pain that is severe, has the sympathetic component of a constant burning pain, but sympathetic block loses its effect due to the long- standing damage to the nerves.

Because of lack of familiarity with such a complex phenomenon, a lot of patient are accused of having never had RSD and they are deprived of treatment due to the SIP component of the pain.

As long as in the early stages of the disease the patient has had SMP (sympathetically maintained pain) confirmed by complete relief of pain to sympathetic nerve blocks, there is no reason to doubt the illness later on when the condition becomes more complicated.

Another factor is that even though Phentolamine IV nerve block relieves the sympathetic pain, attempts at sympathetic nerve block by direct injection to the sympathetic nerve ganglia (such as stellate ganglion block) even in the best of hands and in the hands of the most experienced physicians faces a one-fourth (approximately 25%) risk of the block not being successful due to anatomical variation and due to the fact that the sympathetic ganglion is not exactly where it is supposed to be. So, because of this one-fourth failure rate of technically and successfully blocking the sympathetic ganglion, the RSD cannot be ruled out on the basis of "SIP" diagnosis.

There is no one test in the world that can definitively 100% rule in or rule out RSD. Even IV Phentolamine test is fraught with handicaps of not completely relieving the pain of RSD due to the simultaneous complication of SIP if the patient's original injury has also caused some somatic (non-sympathetic) nerve damage to the area involved with RSD.

As the world literature reflects, the fact that the triphasic bone scan test is successful in only 55 to 65% of the patients[1]. This is due to the fact that RSD not infrequently causes symmetrical bilateral involvement in the extremities also due to the fact that in chronic RSD that has been partially treated the bone scan may be insensitive and may not show the abnormal isotope uptake in the extremities. Thermography is not, by far, 100% positive in RSD patients, and at best has a sensitivity of around 80%. Both bone scan and thermography, like any other test (including MRI and CAT scan), are handicapped by false-positive and false-negative results and showing changes expected in RSD patients when the patient already has had an old injury and does not suffer the full picture of RSD anymore.

The diagnosis of RSD should always be a clinical diagnosis. The diagnosis of RSD cannot be made on the basis of "ruling out other causes". It is an insensitive and inaccurate way of diagnosing RSD.

There is no way one can "rule out" other causes. The patient with cancer, RSD, epilepsy, or any other serious illness can also suffer from the clinical manifestations (conversion reaction) and/or malingering. Just to prove conversion reaction or malingering does not rule out co-existence of cancer, RSD, multiple sclerosis, or other complex and serious illnesses.

The best guideline for the diagnosis of RSD is the presence of the following criteria:

1. A constant burning pain that is elicited even with a breeze or a touch (allodynia).

2. Any manifestation of the disturbance of motor function in the extremity such as constriction of the blood vessels (cold extremity and poor circulation), or movement disorder such as tremor, dystonia and flexion spasm, atrophy or weakness of the muscles of the extremity.

3. Evidence of inflammation (swelling) in the involved area. This may be in the form of simple swelling (edema), skin rash (neuro-dermatitis), spontaneous bleeding, blotchy skin, and other forms of discoloration of the skin.

4. Disturbance of limbic system function. The sensory sympathetic nerve fibers ascend through the spinal cord up to the brainstem and thalamus and terminate in limbic system (marginal system which is at the margin of old and new brain). This system, which is mainly over the temporal lobe and frontal lobe regions, is responsible for control of emotion, expression of proper judgment, and memory function, and control of diurnal cycle (through the brainstem influence on the sleep wakeful cycle).

A true RSD patient suffers from insomnia, agitation, depression, disturbance of judgment manifested by willing to have any type of operation and any other type of treatment that comes by, and complications of attempted suicide, as well as weight fluctuation.

Without some manifestation of the above four categories, one cannot make the diagnosis of RSD. RSD cannot be ruled in or out by trust of exclusion. For example, if the patient has carpal tunnel syndrome secondary to RSD, then the patient's diagnosis is not a simple carpal tunnel syndrome but RSD causing carpal tunnel syndrome, etc.

H. Hooshmand, M.D.

Reference:

1. Lee GW, Weeks PM: The role of bone scintigraphy in diagnosing reflex sympathetic dystrophy. J Hand Surg [Am]. 1995; 20:458-463.

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